US5243454A - Liquid crystal display device having correcting means - Google Patents

Liquid crystal display device having correcting means Download PDF

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Publication number
US5243454A
US5243454A US07/837,901 US83790192A US5243454A US 5243454 A US5243454 A US 5243454A US 83790192 A US83790192 A US 83790192A US 5243454 A US5243454 A US 5243454A
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Prior art keywords
liquid crystal
signal
display device
crystal display
image signal
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Expired - Lifetime
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US07/837,901
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Jumpei Nakamura
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Sony Corp
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Sony Corp
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/13306—Circuit arrangements or driving methods for the control of single liquid crystal cells
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/028—Improving the quality of display appearance by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction

Definitions

  • the present invention generally relates to liquid crystal display devices and, more particularly, is directed to a liquid crystal display device having a large liquid crystal panel.
  • a liquid crystal display device having a large liquid crystal panel In case of performing the display of an image signal in the street, for example, a liquid crystal display device having a large liquid crystal panel is used.
  • the liquid crystal panel since on a display portion of the liquid crystal panel are generally laminated a plurality of masks, the liquid crystal panel has such a property that the luminance thereof differs greatly depending on view angles of a viewer.
  • view angles ⁇ 1 and ⁇ 2 of a viewer B at upper and lower end portions thereof, for example differ greatly as shown in FIG. 1.
  • the display quality of the liquid crystal panel such as luminance thereof changes between the upper and lower end portions for the viewer B, so that the viewer B may feel difficulty in viewing an image on the panel A.
  • a liquid crystal display includes a large liquid crystal panel, whose view angle changes, for displaying an image thereon in accordance with an image signal supplied to the liquid crystal panel, and a correcting circuit for changing a level of the image signal supplied to the liquid crystal panel within a predetermined period to thereby correct the change of display quality of the panel due to the change of the view angle.
  • the level of the image signal is changed within the predetermined period, the change of display quality due to the change of the view angle of the viewer is corrected, so that a viewer can view a good image on the panel.
  • FIG. 1 is a schematic diagram used to explain the drawbacks of the prior-art liquid crystal display device
  • FIG. 2 is a block diagram showing a liquid crystal display device according to an embodiment of the present invention.
  • FIGS. 3A through 3D are waveform diagrams used to explain operation of the liquid crystal display device of FIG. 2.
  • a liquid crystal display device according to an embodiment of the present invention will now be described with reference to FIG. 2 and FIGS. 3A through 3D.
  • FIG. 2 shows in block form a liquid crystal display device according to the embodiment of the present invention.
  • an image signal generated by a signal source 1 is supplied to the base of a transistor 2 whose emitter is grounded through a resistor 3.
  • a signal produced on the emitter of the transistor 2 is applied to a liquid crystal panel 4 and a synchronizing (sync.) signal from the signal source 1 is supplied to the liquid crystal panel 4, whereby the image signal from the signal source 1 is displayed on the liquid crystal panel 4.
  • a vertical sync. signal from the signal source 1 is supplied to a signal generator 5 which generates a sawtooth wave signal or the like.
  • the sawtooth wave signal generated by the signal generator 5 and having a period equal to that of the vertical sync. signal is supplied to the base of a transistor 6.
  • a collector and an emitter of the transistor 6 are connected to a power supply terminal 7 being supplied with a power source voltage Vcc and the collector of the transistor 2, respectively. Further, a capacitor 8 is connected between the collector and the emitter of the transistor 6.
  • the image signal and the vertical sync. signal respectively shown in FIGS. 3A, 3B are delivered from the signal source 1, and the sawtooth wave signal shown in FIG. 3C having a period equal to that of the vertical sync. signal is delivered from the signal generator 5.
  • the liquid crystal panel 4 is supplied with an image signal whose DC level is changed within one field, that is, one vertical period, as shown in FIG. 3D.
  • the liquid crystal panel 4 is constructed such that the display thereof is normally white and a view angle of the viewer is selected to be proper in the display quality at the lower end portion of the panel, due to the change of the view angle, the luminance is changed to be lowered at, for example, the upper side portion of the panel.
  • the image signal is corrected by the arrangement of FIG. 2 in a manner that its DC level is decreased at the upper portion of the panel while increased at the lower portion thereof, whereby the luminance of the display is made higher toward the upper end portion of the panel and lower toward the lower end portion thereof to thereby equalize the luminance of the display all over the liquid crystal panel 4.
  • the DC level of the image signal will be corrected by a sawtooth signal whose polarity is in opposite to that of the sawtooth signal shown in FIG. 3C.
  • the change of the display quality that is, luminance thereof may be corrected by generating a parabolic wave signal in synchronism with a horizontal sync. signal from the signal generator 5 instead of the sawtooth wave signal.
  • the contrast of the display changes depending on the view angle, it may be compensated for by correcting the amplitude of the image signal.
  • the change of display quality due to the change of the view angle of a viewer is corrected, so that a viewer can view a good image on the panel.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Computer Hardware Design (AREA)
  • Optics & Photonics (AREA)
  • Liquid Crystal Display Device Control (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Controls And Circuits For Display Device (AREA)
  • Liquid Crystal (AREA)
  • Transforming Electric Information Into Light Information (AREA)

Abstract

A liquid crystal display includes a large liquid crystal panel, whose view angle changes, for displaying an image thereon in accordance with an image signal supplied to the liquid crystal panel, and a correcting circuit for changing a level of the image signal supplied to the liquid crystal panel within a predetermined period to thereby correct the change of display quality of the panel due to the change of the view angle.

Description

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to liquid crystal display devices and, more particularly, is directed to a liquid crystal display device having a large liquid crystal panel.
2. Description of the Prior Art
In case of performing the display of an image signal in the street, for example, a liquid crystal display device having a large liquid crystal panel is used. In the liquid crystal display device, however, since on a display portion of the liquid crystal panel are generally laminated a plurality of masks, the liquid crystal panel has such a property that the luminance thereof differs greatly depending on view angles of a viewer. Thus, when a large liquid crystal panel A is used, view angles θ1 and θ2 of a viewer B at upper and lower end portions thereof, for example, differ greatly as shown in FIG. 1. If the difference of the view angles θ1 and θ2 is not less than a predetermined value, the display quality of the liquid crystal panel such as luminance thereof changes between the upper and lower end portions for the viewer B, so that the viewer B may feel difficulty in viewing an image on the panel A.
OBJECTS AND SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an improved liquid crystal display device having a large liquid crystal panel in which the aforementioned shortcomings and disadvantages encountered with the prior art can be eliminated.
More specifically, it is an object of the present invention to provide a liquid crystal display device having a large liquid crystal panel which can prevent the change of display quality of the liquid crystal panel due to differences of view angles from a viewer so that the viewer can view a good image on the panel.
As an aspect of the present invention, a liquid crystal display includes a large liquid crystal panel, whose view angle changes, for displaying an image thereon in accordance with an image signal supplied to the liquid crystal panel, and a correcting circuit for changing a level of the image signal supplied to the liquid crystal panel within a predetermined period to thereby correct the change of display quality of the panel due to the change of the view angle.
Thus, since the level of the image signal is changed within the predetermined period, the change of display quality due to the change of the view angle of the viewer is corrected, so that a viewer can view a good image on the panel.
The preceding and other objects, features, and disadvantages of the present invention will become apparent from the following detailed description of an illustrative embodiment thereof when read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram used to explain the drawbacks of the prior-art liquid crystal display device;
FIG. 2 is a block diagram showing a liquid crystal display device according to an embodiment of the present invention; and
FIGS. 3A through 3D are waveform diagrams used to explain operation of the liquid crystal display device of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A liquid crystal display device according to an embodiment of the present invention will now be described with reference to FIG. 2 and FIGS. 3A through 3D.
FIG. 2 shows in block form a liquid crystal display device according to the embodiment of the present invention.
Referring to FIG. 2, an image signal generated by a signal source 1 is supplied to the base of a transistor 2 whose emitter is grounded through a resistor 3. A signal produced on the emitter of the transistor 2 is applied to a liquid crystal panel 4 and a synchronizing (sync.) signal from the signal source 1 is supplied to the liquid crystal panel 4, whereby the image signal from the signal source 1 is displayed on the liquid crystal panel 4.
A vertical sync. signal from the signal source 1 is supplied to a signal generator 5 which generates a sawtooth wave signal or the like. The sawtooth wave signal generated by the signal generator 5 and having a period equal to that of the vertical sync. signal is supplied to the base of a transistor 6. A collector and an emitter of the transistor 6 are connected to a power supply terminal 7 being supplied with a power source voltage Vcc and the collector of the transistor 2, respectively. Further, a capacitor 8 is connected between the collector and the emitter of the transistor 6.
In the thus arranged liquid crystal display device, the image signal and the vertical sync. signal respectively shown in FIGS. 3A, 3B are delivered from the signal source 1, and the sawtooth wave signal shown in FIG. 3C having a period equal to that of the vertical sync. signal is delivered from the signal generator 5. Thus, the liquid crystal panel 4 is supplied with an image signal whose DC level is changed within one field, that is, one vertical period, as shown in FIG. 3D.
When the liquid crystal panel 4 is constructed such that the display thereof is normally white and a view angle of the viewer is selected to be proper in the display quality at the lower end portion of the panel, due to the change of the view angle, the luminance is changed to be lowered at, for example, the upper side portion of the panel. In such a case, the image signal is corrected by the arrangement of FIG. 2 in a manner that its DC level is decreased at the upper portion of the panel while increased at the lower portion thereof, whereby the luminance of the display is made higher toward the upper end portion of the panel and lower toward the lower end portion thereof to thereby equalize the luminance of the display all over the liquid crystal panel 4.
According to the arrangement shown in FIG. 2, since the level of the image signal from the signal source 1 is changed within every predetermined period by the circuit arrangement including the transistors 2, 6 and the signal generator 5, the change of display quality of the liquid crystal panel 4 due to the change of the view angle of the viewer is corrected, so that the viewer can view a good image on the panel.
When the liquid crystal panel 4 of the arrangement shown in FIG. 2 is arranged such that its display is normally black, the DC level of the image signal will be corrected by a sawtooth signal whose polarity is in opposite to that of the sawtooth signal shown in FIG. 3C. Further, when the view angle changes greatly between the right and left end portions of the liquid crystal panel 4, the change of the display quality, that is, luminance thereof may be corrected by generating a parabolic wave signal in synchronism with a horizontal sync. signal from the signal generator 5 instead of the sawtooth wave signal. Furthermore, when the contrast of the display changes depending on the view angle, it may be compensated for by correcting the amplitude of the image signal.
As set out above, according to the present invention, since the level of the image signal is changed within every predetermined period, the change of display quality due to the change of the view angle of a viewer is corrected, so that a viewer can view a good image on the panel.
Having described the preferred embodiment of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to that precise embodiment and that various changes and modifications thereof could be effected by one skilled in the art without departing from the spirit or scope of the invention as defined in the appended claims.

Claims (5)

What is claimed is:
1. A liquid crystal display device comprising:
a large liquid crystal panel, whose view angle changes, for displaying an image thereon in accordance with an image signal supplied to said liquid crystal panel; and
correcting means for changing a level of the image signal supplied to said liquid crystal panel within a predetermined period to thereby correct change of display quality of said panel due to the change of the view angle.
2. A liquid crystal display device according to claim 1, wherein said correcting means includes means for generating a sawtooth signal in synchronous with a vertical sync. signal of said image signal and means for superimposing the sawtooth signal on the image signal supplied to said panel.
3. A liquid crystal display device according to claim 1, wherein said correcting means includes means for generating a parabolic wave signal in synchronism with a horizontal sync. signal and means for superimposing the parabolic signal on the image signal supplied to said panel.
4. A liquid crystal display device according to claim 1, wherein said correcting means includes means for correcting an amplitude of the image signal.
5. A liquid crystal display device according to claim 1, wherein said predetermined period is a vertical synchronizing period of the image signal.
US07/837,901 1991-02-26 1992-02-20 Liquid crystal display device having correcting means Expired - Lifetime US5243454A (en)

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JP3-31106 1991-02-26
JP3031106A JPH04270379A (en) 1991-02-26 1991-02-26 Liquid crystal display device

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5650796A (en) * 1991-03-08 1997-07-22 Hitachi, Ltd. Matrix liquid crystal display having function to correct viewing angle
US5815133A (en) * 1992-11-17 1998-09-29 Canon Kabushiki Kaisha Display apparatus
US5835074A (en) * 1992-12-30 1998-11-10 Advanced Displays Corporation Method to change the viewing angle in a fixed liquid crystal display by changing the pre-tilt angle in the liquid crystal layer with a bias voltage
FR2765024A1 (en) * 1997-06-20 1998-12-24 Sextant Avionique Polarisation of LCD screen as function of its viewing angle
US20020149575A1 (en) * 2001-02-19 2002-10-17 Samsung Electronics Co., Ltd. Liquid crystal display adaptive to viewing angle

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3868674A (en) * 1971-12-09 1975-02-25 Philips Corp Visual display apparatus including a liquid crystal display panel
JPS5324849A (en) * 1976-08-19 1978-03-08 Sharp Corp Drive system for display device
JPS5893030A (en) * 1981-11-30 1983-06-02 Sony Corp Driving circuit of electronic shutter
JPS61284732A (en) * 1985-06-10 1986-12-15 Casio Comput Co Ltd Driving method of liquid crystal display device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3868674A (en) * 1971-12-09 1975-02-25 Philips Corp Visual display apparatus including a liquid crystal display panel
JPS5324849A (en) * 1976-08-19 1978-03-08 Sharp Corp Drive system for display device
JPS5893030A (en) * 1981-11-30 1983-06-02 Sony Corp Driving circuit of electronic shutter
JPS61284732A (en) * 1985-06-10 1986-12-15 Casio Comput Co Ltd Driving method of liquid crystal display device

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
IBM, "Programmable viewing angle control for a liquid crystal display", IBM Technical Disclosure Bulletin, vol. 30, No. 3, Aug. 1987.
IBM, Programmable viewing angle control for a liquid crystal display , IBM Technical Disclosure Bulletin, vol. 30, No. 3, Aug. 1987. *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5650796A (en) * 1991-03-08 1997-07-22 Hitachi, Ltd. Matrix liquid crystal display having function to correct viewing angle
US5815133A (en) * 1992-11-17 1998-09-29 Canon Kabushiki Kaisha Display apparatus
US5835074A (en) * 1992-12-30 1998-11-10 Advanced Displays Corporation Method to change the viewing angle in a fixed liquid crystal display by changing the pre-tilt angle in the liquid crystal layer with a bias voltage
US6236384B1 (en) 1992-12-30 2001-05-22 Universal Avionics Systems Corporation-Instrument Division And L-3 Method to change the viewing angle in a fixed liquid crystal display by changing the pre-tilt angle in the liquid crystal layer with a bias voltage
FR2765024A1 (en) * 1997-06-20 1998-12-24 Sextant Avionique Polarisation of LCD screen as function of its viewing angle
US20020149575A1 (en) * 2001-02-19 2002-10-17 Samsung Electronics Co., Ltd. Liquid crystal display adaptive to viewing angle
US20070030223A1 (en) * 2001-02-19 2007-02-08 Seung-Hwan Moon Liquid crystal display adaptive to viewing angle
US7639224B2 (en) 2001-02-19 2009-12-29 Samsung Electronics Co., Ltd. Liquid crystal display adaptive to viewing angle

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